1. Field of the Invention
The prevent invention relates to a bearing vibration measuring apparatus and a bearing vibration measuring method for detecting a defect of a bearing based on vibration generated from the bearing and a radial type bearing vibration of which is measured by a bearing vibration measuring apparatus.
2. Description of the Related Art
There is known a bearing vibration measuring apparatus 70 shown in FIG. 12 as an example of a bearing vibration measuring apparatus of a related art (refer to, for example, JP-A-2002-350289 (pages 2 through 4, FIG. 1)).
In the bearing vibration measuring apparatus 70, a straight arbor 73 is fitted to an inner ring 72 of a bearing 71, and the straight arbor 73 is connected to a rotating main spindle of a motor 74. The motor 74 is supplied with an alternating current power from an inverter 75 and is rotated at a resolution number in accordance with a frequency of the alternating current power. A pickup 77 is arranged to be opposed to an outer circumferential face 76a of an outer ring 76 of the bearing 71 with a predetermined clearance therebetween, and the pickup 77 detects vibration generated from the outer ring 76. A vibrating signal detected by the pickup 77 is subjected to amplification and signal processing by an amplifier 78 and a waveform of the vibrating signal is recorded by a predetermined waveform recording apparatus.
Further, the bearing vibration measuring apparatus 70 is provided with a press rotating unit 79 for rotating the outer ring 76 of the bearing 71 while pressing the outer ring 76 in an axial direction. The press rotating unit 79 includes a pressing jig 80 for pressing an end face 76b in an axial direction of the outer ring 76; an inclined rotating shaft 81 connected to the pressing jig 80 and inclined to a center axis J0 of the straight arbor 73, and a self-rotating pulley 82 fixed to an end of the inclined rotating shaft 81. The inclined rotating shaft 81 is supported at substantially both ends thereof in the axial direction by bearings (not illustrated) on an inner circumferential side of an inner cylinder (not illustrated).
In the bearing vibration measuring apparatus 70, the motor 74 is rotated at a predetermined revolution number by supplying the alternating current power from the inverter 75 to the motor 74 to there by rotate the inner ring 72 of the bearing 81 integrally with the arbor 73. At the same time, the press rotating unit 79 rotates the pulley 82 and a pulley 85 by driving a motor 83 and a motor 84 while pressing the end face 76b of the outer ring 76 of the bearing 71 by the pressing jig 80. Thereby, while the pressing jig 80 is being self-rotated by constituting a rotating shaft by a self-rotating shaft J1, by a resolution number lower than that of the self-rotation, the inner cylinder axially supporting the shaft 81 is rotated. By rotating the inner cylinder on an inner side of an outer cylinder, a through hole of the inner cylinder is made to whirl relative to the rotating axis J0 of the arbor 73, and thus while the shaft 81 is being self-rotated on the self-rotating axis J1, the self-rotating axis J1 is made to whirl at a surrounding of the rotating axis J0 at a speed slower than the self-rotating speed and the shaft 81 carries out a precession movement to thereby subject the pressing jig 80 also to the precession movement. Thereby, there is detected a flaw or an inclusion present from vicinities of shoulders to vicinities of bottoms in track faces of the inner ring 72 and the outer ring 76 of the bearing 71.
However, in the above-described bearing vibration measuring apparatus 70, the press rotating unit 79 for making the pressing jig 80 carry out the precession movement is provided with a complicated structure and therefore, the apparatus is expensive. Further, the inclination of the outer ring 76 is uniquely determined by a shape of the pressing jig 80 and therefore, there is needed a pressing jig in correspondence with a desired inclination of the outer ring. Further, in detecting a flaw in applying a correct thrust load to the outer ring 76 or in detecting a shape component of the inner ring 72 or the outer ring 76 by vibration such as a waviness or the like, it is necessary to measure the flaw or the shape component by applying the correct thrust load to the outer ring 76. However, since the pressing jig 80 is provided with a shape of inclining the outer ring 76 and therefore, the correct thrust load cannot be applied thereto. Furthermore, only a single kind of a mode of inclining the outer ring 76 is provided by the shape of the pressing jig 80 and therefore, there is a high possibility in measurement by the bearing vibration measuring apparatus 70 that a bearing having a defect is determined to be an acceptable product.